Nucleotide binding to chloroplast coupling factor and ATPase activity

1986 ◽  
Vol 14 (1) ◽  
pp. 45-46 ◽  
Author(s):  
BERNHARD HUCHZERMEYER
Keyword(s):  
Atpase Activity ◽  
Nucleotide Binding ◽  
Coupling Factor ◽  
Chloroplast Coupling Factor

Phosphate Binding to Isolated Chloroplast Coupling Factor (CF1)

1988 ◽  
Vol 43 (3-4) ◽  
pp. 213-218 ◽  
Author(s):  
Bernhard Huchzermeyer
Keyword(s):  
Atpase Activity ◽  
Binding Site ◽  
Inorganic Phosphate ◽  
Coupling Factor ◽  
Binding Domain ◽  
Atp Binding ◽  
Phosphate Binding ◽  
Chloroplast Coupling Factor ◽  
Single Binding Site ◽  
Site Binding

A single binding site for phosphate was found on isolated chloroplast coupling factor in the absence of nucleotides. In our experiments the phosphate binding site showed a Kd of 170 μᴍ. We did not observe any differences whether the ATPase activity of CF] had been activated or not. If the enzyme was incubated with [γ-32P]ATP the amount of 32P bound per CF1 depended on the pretreatment of the enzyme: In the presence of ADP no ATP or phosphate was bound to CF,. After activation of ATPase activity one mol of ATP per mol CF, was rapidly bound and hydrolyzed while there was a slowly occurring binding of another phosphate without concomitant nucleotide binding. We conclude that there are two different types of phosphate binding observed in our experiments: 1) Inorganic phosphate can be bound by one catalytic site per mol of CF1 2) The γ-phosphate of ATP is able to bind to an ATP binding domain of the enzyme if this domain can exchange substrates with the incubation medium. This ATP binding domain appears to differ from the site binding inorganic phosphate, because at least a portion of the coupling factor contains more than one labelled phosphate during our ATPase tests.

Energy Transfer Inhibition Induced by Nitrofen

1982 ◽  
Vol 37 (9) ◽  
pp. 787-792 ◽  
Author(s):  
Bernhard Huchzermeyer
Keyword(s):  
Energy Transfer ◽  
Atpase Activity ◽  
Enzymatic Activity ◽  
Strong Correlation ◽  
Coupling Factor ◽  
Regulatory Effect ◽  
Nucleotide Exchange ◽  
Chloroplast Coupling Factor ◽  
Transfer Inhibitor ◽  
Transfer Inhibition

The herbicide nitrofen was shown to act as an energy transfer inhibitor. The results proved nitrofen to act by inhibiting nucleotide exchange on the chloroplast coupling factor. A strong correlation was found between the inhibition of phosphorylation, ATPase activity, and nucleotide exchange. These results are discussed in terms of a regulatory effect of tightly bound ADP on the enzymatic activity of the chloroplast coupling factor.

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